block: always use I_BDEV on file->f_mapping->host to find the bdev

Always use I_BDEV(file->f_mapping->host) to find the bdev for a file to
free up file->private_data for other uses.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230608110258.189493-29-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/fops.c

@@ -54,7 +54,7 @@ static bool blkdev_dio_unaligned(struct block_device *bdev, loff_t pos,
 static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
 		struct iov_iter *iter, unsigned int nr_pages)
 {
-	struct block_device *bdev = iocb->ki_filp->private_data;
+	struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
 	struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
 	loff_t pos = iocb->ki_pos;
 	bool should_dirty = false;
@@ -170,7 +170,7 @@ static void blkdev_bio_end_io(struct bio *bio)
 static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
 		unsigned int nr_pages)
 {
-	struct block_device *bdev = iocb->ki_filp->private_data;
+	struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
 	struct blk_plug plug;
 	struct blkdev_dio *dio;
 	struct bio *bio;
@@ -310,7 +310,7 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
 					struct iov_iter *iter,
 					unsigned int nr_pages)
 {
-	struct block_device *bdev = iocb->ki_filp->private_data;
+	struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
 	bool is_read = iov_iter_rw(iter) == READ;
 	blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
 	struct blkdev_dio *dio;
@@ -451,7 +451,7 @@ static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
 static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
 		int datasync)
 {
-	struct block_device *bdev = filp->private_data;
+	struct block_device *bdev = I_BDEV(filp->f_mapping->host);
 	int error;
 
 	error = file_write_and_wait_range(filp, start, end);
@@ -516,17 +516,15 @@ static int blkdev_open(struct inode *inode, struct file *filp)
 	if (IS_ERR(bdev))
 		return PTR_ERR(bdev);
 
-	filp->private_data = bdev;
 	filp->f_mapping = bdev->bd_inode->i_mapping;
 	filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 	return 0;
 }
 
 static int blkdev_release(struct inode *inode, struct file *filp)
 {
-	struct block_device *bdev = filp->private_data;
-
-	blkdev_put(bdev, (filp->f_mode & FMODE_EXCL) ? filp : NULL);
+	blkdev_put(I_BDEV(filp->f_mapping->host),
+		   (filp->f_mode & FMODE_EXCL) ? filp : NULL);
 	return 0;
 }
 
@@ -539,7 +537,7 @@ static int blkdev_release(struct inode *inode, struct file *filp)
  */
 static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
-	struct block_device *bdev = iocb->ki_filp->private_data;
+	struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
 	struct inode *bd_inode = bdev->bd_inode;
 	loff_t size = bdev_nr_bytes(bdev);
 	size_t shorted = 0;
@@ -575,7 +573,7 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
 static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
-	struct block_device *bdev = iocb->ki_filp->private_data;
+	struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
 	loff_t size = bdev_nr_bytes(bdev);
 	loff_t pos = iocb->ki_pos;
 	size_t shorted = 0;